Development of analytical methodologies for iodine species in gaseous and particulate phases of the coastal atmosphere

It has been demonstrated that iodine does have an important influence on atmospheric chemistry, especially the formation of new particles and the enrichment of iodine in marine aerosols. It was pointed out that the most probable chemical species involved in the production or growth of these particles are iodine oxides, produced photochemically from biogenic halocarbon emissions and/or iodine emission from the sea surface. However, the iodine chemistry from gaseous to particulate phase in the coastal atmosphere and the chemical nature of the condensing iodine species are still not understood. A Tenax / Carbotrap adsorption sampling technique and a thermo-desorption / cryo-trap / GC-MS system has been further developed and improved for the volatile organic iodine species in the gas phase. Several iodo-hydrocarbons such as CH3I, C2H5I, CH2ICl, CH2IBr and CH2I2 etc., have been measured in samples from a calibration test gas source (standards), real air samples and samples from seaweeds / macro-algae emission experiments. A denuder sampling technique has been developed to characterise potential precursor compounds of coastal particle formation processes, such as molecular iodine in the gas phase. Starch, TMAH (TetraMethylAmmonium Hydroxide) and TBAH (TetraButylAmmonium Hydroxide) coated denuders were tested for their efficiencies to collect I2 at the inner surface, followed by a TMAH extraction and ICP/MS determination, adding tellurium as an internal standard. The developed method has been proved to be an effective, accurate and suitable process for I2 measurement in the field, with the estimated detection limit of ~0.10 ng∙L-1 for a sampling volume of 15 L. An H2O/TMAH-Extraction-ICP/MS method has been developed for the accurate and sensitive determination of iodine species in tropospheric aerosol particles. The particle samples were collected on cellulose-nitrate filters using conventional filter holders or on cellulose nitrate/tedlar-foils using a 5-stage Berner impactor for size-segregated particle analysis. The water soluble species as IO3- and I- were separated by anion exchanging process after water extraction. Non-water soluble species including iodine oxide and organic iodine were digested and extracted by TMAH. Afterwards the triple samples were analysed by ICP/MS. The detection limit for particulate iodine was determined to be 0.10~0.20 ng•m-3 for sampling volumes of 40~100 m3. The developed methods have been used in two field measurements in May 2002 and September 2003, at and around the Mace Head Atmospheric Research Station (MHARS) located at the west coast of Ireland. Elemental iodine as a precursor of the iodine chemistry in the coastal atmosphere, was determined in the gas phase at a seaweed hot-spot around the MHARS, showing I2 concentrations were in the range of 0~1.6 ng∙L-1 and indicating a positive correlation with the ozone concentration. A seaweed-chamber experiment performed at the field measurement station showed that the I2 emission rate from macro-algae was in the range of 0.019~0.022 ng•min-1•kg-1. During these experiments, nanometer-particle concentrations were obtained from the Scanning Mobility Particle Sizer (SMPS) measurements. Particle number concentrations were found to have a linear correlation with elemental iodine in the gas phase of the seaweeds chamber, showing that gaseous I2 is one of the important precursors of the new particle formation in the coastal atmosphere. Iodine contents in the particle phase were measured in both field campaigns at and around the field measurement station. Total iodine concentrations were found to be in the range of 1.0 ~ 21.0 ng∙m-3 in the PM2.5 samples. A significant correlation between the total iodine concentrations and the nanometer-particle number concentrations was observed. The particulate iodine species analysis indicated that iodide contents are usually higher than those of iodate in all samples, with ratios in the range of 2~5:1. It is possible that those water soluble iodine species are transferred through the sea-air interface into the particle phase. The ratio of water soluble (iodate + iodide) and non-water soluble species (probably iodine oxide and organic iodine compounds) was observed to be in the range of 1:1 to 1:2. It appears that higher concentrated non-water soluble species, as the products of the photolysis from the gas phase into the particle phase, can be obtained in those samples while the nucleation events occur. That supports the idea that iodine chemistry in the coastal boundary layer is linked with new particle formation events. Furthermore, artificial aerosol particles were formed from gaseous iodine sources (e.g. CH2I2) using a laboratory reaction-chamber experiment, in which the reaction constant of the CH2I2 photolysis was calculated to be based upon the first order reaction kinetic. The end products of iodine chemistry in the particle phase were identified and quantified.

Functional polymer based nanoparticles : development of defined complex structures as basis for in-vitro and in-vivo applications

In Rahmen der vorliegenden Arbeit wurde ein neuartiger Zugang zu einer Vielzahl von Polymerstrukturen auf Basis des klinisch zugelassenen Polymers Poly(N-(2-Hydroxypropyl)-methacrylamide) (PHPMA) entwickelt. Der synthetische Zugang beruht zum einen auf der Verwendung von Reaktivesterpolymeren und zum anderen auf der Reversible Addition Fragmentation Chain Transfer (RAFT) Polymerisationsmethode. Diese Form einer kontrollierten radikalischen Polymerisation ermöglichte es, neben der Synthese von besser definierten Homopolymeren auch statistische und Blockcopolymere herzustellen. Die Reaktivesterpolymere können durch einfache Aminolyse in HPMA-basierte Systeme überführt werden. Somit können sie als eine vielversprechende Basis zur Synthese von umfangreichen Polymerbibliotheken angesehen werden. Die hergestellten Polymere kombinieren verschiedene Funktionalitäten bei konstantem Polymerisationsgrad. Dies ermöglicht eine Optimierung auf eine gezielte Anwendung hin ohne den Parameter der Kettenlänge zu verändern.rnIm weiteren war es durch Verwendung der RAFT Polymerisation möglich partiell bioabbaubare Blockcopolymere auf Basis von Polylactiden und HPMA herzustellen, in dem ein Kettentransferreagenz (CTA) an ein wohl definiertes Polylactid Homopolymer gekoppelt wurde. Diese Strukturen wurden in ihrer Zusammensetzung variiert und mit Erkennungsstrukturen (Folaten) und markierenden Elementen (Fluoreszenzfarbstoffe und +-emittierenden Radionukleide) versehen und im weiteren in vitro und in vivo evaluiert.rnAuf Grund dieser Errungenschaften war es möglich den Einfluss der Polymermikrostruktur auf das Aggregationsverhalten hin mittel Lichtstreuung und Fluoreszenzkorrelationsspektroskopie zu untersuchen. Es konnte gezeigt werden, dass erst diese Informationen über die Überstrukturbildung die Kinetik der Zellaufnahme erklären können. Somit wurde die wichtige Rolle von Strukturwirkungsbeziehungen nachgewiesen.rnSomit konnte neben der Synthese, Charakterisierung und ersten biologischen Evaluierungen ein Beitrag zum besseres Verständnis zur Interaktion von polymeren Partikeln mit biologischen Systemen geleistet werden.